When do i use sine rule

Where a and b represents the length of the side of the triangle and A and B represents the angle of the triangle. The cosine rule provides a relationship between the lengths of the sides a triangle to the cosine of its opposite angles. Just as is in the image, the cosine rule relates the length, a to its opposite angle, A. Tangent rule relates the tangents of two angles to the length of the opposite sides of the triangle.

We make use of tangent rule. Always, remember to add length units whenever you are done calculating the length of a side of a triangle. For Example: the length of the side, a of the triangle from the calculation above is Nickzom Calculator — The Calculator Encyclopedia is capable of calculating problems on sine rule, cosine rule and tangent rule.

To get the answer and workings of calculations on sine rule, cosine rule and tangent rule using the Nickzom Calculator — The Calculator Encyclopedia. First, you need to obtain the app. This does not work because you have no angle measurement.

This does not work because the known angle is not opposite either of the known sides. This does not work because the known side is not opposite either of the known angles. Write the portion of the law of sines that you need. The law of sines works to help you find one piece of information about a triangle -- a side or an angle measurement -- if you know three others. While the full law of sines is written as a three-part equation, you only need to equate two for the rule to work.

The important thing to remember is that you are comparing ratios. The ratio of any side to its opposing angle is equal to the ratio of any other side to its opposing angle. Fill in the numbers that you know. Find the length of side B. Rearrange to solve for the unknown information. Use basic algebra to maneuver the unknown information to stand alone on either side of the equation.

You can then reduce the problem to find the answer. Different calculators operate differently. With some calculators, you will enter your angle measurement first and then the "sin" button. With others, you will enter the "sin" button first and then the angle measurement. You will have to experiment with your calculator. Alternatively, there are some tables available either in math books or online. With a trigonometry table, you can find your desired angle measure in one column and the corresponding value of sine, cosine or tangent in another column.

Part 3. Solve for an unknown angle. Suppose, as a different problem, that you know two sides and need to solve an unknown angle. Use the inverse function if needed to find the angle.

In the above example, the law of sines provides the sine of the selected angle as its solution. To find the measure of the angle itself, you must use the inverse sine function. This is also called the arcsine. Use this to find the measure of the angle. Solve a problem with incomplete information. Find the measurement of all sides and angles for the triangle. First, you should recognize that you do not yet have enough information for the sine rule to apply. The sine rule requires that you have at least one pair with an angle that opposes a known side.

However, you can calculate the third angle of this triangle using simple subtraction. Now solve for the final remaining side. You now have all three angles, 30, 50 and degrees, and all three sides, 5. Sine tables usually only go from 0 to 90 degrees, so before you use it you will have to relate sin to an angle in that range. Look up sin 39 in the table and report that as the answer to sin Yes No. Side a faces angle A, side b faces angle B and side c faces angle C.

When we divide side a by the sine of angle A it is equal to side b divided by the sine of angle B , and also equal to side c divided by the sine of angle C. The answers are almost the same! They would be exactly the same if we used perfect accuracy. Not really, look at this general triangle and imagine it is two right-angled triangles sharing the side h :. The sine of an angle is the opposite divided by the hypotenuse, so:.